Automotive brake



Aug. i3, 1929. G. w. CARLSON AUTOMOTIVE BRAKE Filed Feb. 11, 1925 Patented Aug. 1 3, 1929'.

-f UNITED STATES l l 1,724,452" PATENT A.OI`=FIVI.C"IE.-

' eUsTAV vv.l CARLSON; OF CLEVELAND, OHIO, As'sIGNOR To THE RATON AXLE e;

SPRING COMPANY, OF CLEVELAND, OHIO, A CORPORATION oF OHIO.

f AUTOMOTIVE BRAKE.

Application led February 11, 1925. Serial No. 8,338.

My invention relates to brakes and more *particularly to internal expanding brakes of the so called self energizing type such as are adapted for use on automotive vehicles.'

Heretofore in this type of `brake It has been found that the brake is not nearly as eficient when the member .to be braked is rotating in a rearward direction. That 1s, lthe self energizing action which takes place l" in forward rotation is greatly lacking 1n rearward rotation of the brake drum.

The chief object ofthis invention 1s to provide a brake which will give a substantially equal self energizing actlon upon rear- 5 ward or forward rotation of the brake drum. The invention consists in the novel feaf4 'tures arrangements and combination of parts :eml odied inthe apparatus hereinafter described as illustrating the preferred formk o of the invention. andthe invention will be more particularly pointed out in the appended claims.

Further objects and advantages of the 1nvention will more fully appear from the f ollowing description taken in connection wlth the accompanying drawings which show, by way of example, the preferred embodiment of the invention.

Referring to the drawings Fig. 1 illustrates the brake and parts as sociated directly therewith, partly in section.

Fig. 2 is a-e of Fig. 1.

3 is a sectional view taken on line 3 3 of Fig. 1.

Fig. 4 is a. sectional view taken on line 44 of Fig. 1.

Referring to Fig-1, 1 represents the axle to which the brake is to be applied; in this yembodiment the rear axle of an automotive vehicle A hub 2 is keyed to the axle 1 and isadapted to carry the vehicle wheel (not shown), to which is attached the brake drum 3, so that as the axle 1 rotates the hub ro- 5 tates, together with the wheel and the brake drum 3. A non-rotatable part such as'the :axle housing 4 carriesy a dust shield 5 fastened thereto as by rivets 6; The dust shield 5 is provided with a projecting pin 7 which extends toward the head 3 (Fig. 3) Of the brake drum 3. The pin 7 provides bearing portions against which the brake shoes abut, for purposes next to be explained, land may :be termed an anchor pin.

pivotally connected to shackle ends 12 and 13 a sectional view taken on line` of the shield 5 an actuating arm 28 is secured- The relatively rigid brake shoes 8 and 9 bearing portions of the pin 7. At their other ends the shoes 8 and 9 are respectively v by means of the pins 14 and 15. The shackle ends 12 and 13 are provided respectively with leftand yright hand female threads in .cooperative engagement with a turnbuckle bolt 1.6, th-us providing an adjustable pivotal connection between these adjacent ends of then brake shoes 8 and 9. The pivots 14 and 15 together with the connecting turnbuckle members 12, 1'3 and 16 form in etfecta f double pivotal connection which allows' 70 greater freedom of movement of the/shoes 8 and 9. The shoes 8 and 9 thus connected may bel considered as a single expansible brake means which is adjustable lengthwise' to thereby vary its peripheral length. 11e-"75 'placeable friction elements 8 and 9 are preferably attached, respectively, to` the y shoes 8 and 9, as is Well understood in the art.:

The shoe 9 is provided with a4 slot 17, adjacent the pivoted end thereof, (Fig. 3) into which extends the free end of a guide clip 18 fastened to thedust shield 5 as b rivets .19. This arrangement holds the bra e shoes against axial movement with respect tothe drum 3.

' A toggle link 20'is pivotally connectedA at one end to the shoe 8 adjacent the end 10; and a toggle link 21 is pivotally connectedv f at one endito the shoe 9 adjacent the end 11. 90 The opposite ends of the toggle links 20 and 21 are pivotally connected by means of a pin 22, which carries a link plate 23. This link 23 is pivoted at its-other end an arm 24 keyed or otherwise secured upon a stub shaft 25, supported in a bearing plate 26 attached to the dust shield 5 by rivets 27, and free to rotate in said bearing. On the Opposite side,"-

to the other end of the shaft 25, which projects beyond the Outside of the dust shield 5. This arm 28 is adapted.l to be connectedto suitable control elements convenient to the operator. It will therefore be seen that by means of the links 2O and 21 and link plate 23 which is pivoted to the Outer end of the' arm 24 andy by means of the pins l14 and 15,`

the brake segments 8 and 9 are supported in 55 are-provided respectively with concave free `ends 10 and-11 adaptedto bear against the ing against a portion of the pin 7. Similarly y a second tension coil spring 30, less resilient vthan the spring 29, is connected to the link plate 23 and the shoe 9 and serves to hold the lend 11 of the shoe 9 toward the pin 7 in a similar manner.

The brake shoe 9 is provided with a lboss 3l at a point intermediateits two ends. This boss (Fig. 2) is provided with a central bore 32, and a connecting central bore 33, with a shoulder 34 betweenV these bores. A com! pression coil spring 35, less resilient than the spring 30, is -seated in t-he bore 32 with one end bearing against one side of the shoulder 34. A plunger pin 36, provided with a cylindrical head portion 37 adapted to slide within the bore 32, passes axially through the spring 3'5 and pastthe shoulder 34,A and is threaded to engage a nut 38; thereby providing for the adjustment of the spring between the shoulder34 and the head 37. An

extension bracket 39 is secured to the dust shield 5 by the rivets 40, and carries a set screw 41 in threaded engagement therewith and adaptedto act as a stop for the `head 37 of the bolt 36. A lock nut 42 is adapted Eo lock the set screw 41 in the desired posi- 1011.

It will be seen from the foregoing that the brake shoes are 'resiliently supported by the three springs 29, 30 and -35 which cooperatively normally hold the shoes in abutting engagement with .the anchor pin 7 and pro'perly positioned in non-breaklng engagement with respect )to the drum 3. The spring 35 being the least resilient, the shoes are normally resiliently held in fixed spaced relation with respect to the drum 3 in a degree which depends upon the setting of the screw 41. In other words the spring 29 holds the shoe 8 against the anchor pin 7, and tends to hold this shoe away from the adj acent side of the drum 3: but the spring 30 being less resilient, in I'addition to holding the shoe 9 agalnst the pin 7, overcomes the action of the spring 29 and forces the shoes 9 -and 8 toward the side ofthe drum vadjacent the shoe 8. The stop 41 limits this action'by engaging the yieldableplunger 37 resiliently held in position by the spring 35 which, being less resilient than the spring 30 is not overcome thereby. This' yieldablel s-top means thereby centers thebrake elements with respect to the drum .3; but permits the movement of these elements peripherallyv of the drum 3, as will bebetter understood from the following:

ing description of the operation.

Operation In the following description the shoes 8 and 9 and the connecting means will be collectively termed brake means.v

First the drum 3 will be considered with its rotative direction as indicated by the full line arrow at the top of Fig.` l: this will be taken as rearward rotation of the drum. The arm 28 is moyed to the left, in an anticlockwise direction, and with it the arin 24; thereby moving the pin 22 toward the anchor pin 7 and) moving the levers 20 and21 more nearly into alignment to thereby rela-v tively separate the shoes 8 and 9. This tends to movethe ends 10 and ll away from the anchor pin 7; but as soon as the drum is sufficiently engaged by the brake means to overcome the centering 'action of the spring 35, the drum frictionally pulls the shoe 9 until the spring 35 is compressed. The shoe 9 therefore moves in a clockwise direction pushing the shoe 8 toward the stop 7 until the end 10 is in lirm abutting engagement I thereagainst. With the parts in this position, the greater the torque of the drum the greater will be the tendency-for the brake means to grip the drum: due to the tendency of the brake means to wrap or straighten out as aresult of the frictional pull of thedrum 3. 'The pin 7 acts as a fulcrum'about which the brake means moves or wraps, thereby causingthe torque exerted by the drum against the brake means to be translated into a radial force delivered to the drum by the brake means. This increased breaking force is a direct result of the self energizing action and is increased in proportion tothe increase in the torque of the,

drum; so that with a constant force applied to the actuating armv 28 the Veffective braking i action will be in direct proportion to the torque of the drum-swhich, will be in direct proportion to the torque energy exerted by the drum. p

Due to the double pivotal connection comprising the pins 14 and 15,l the segments 8 and 9 a-re always in a fully floating condition; thatis, they always readily assume a concentric positlon with respect to the inner periphery of the member 3, whenthe brake se ments are movedintoI operative position. is' is Ia `great advantage of the double pivotal connection; and is not possible with a single pivotal connection here tofore used, which necessarilyprestricts thel brake segments to an eccentric position with iso Y gizing force is substantially equal to the' resqilect to the drum and causes unequal braking, with consequent unequal Wearing of the Ibrake lining. Thus it Will be s een that each self energizing force resulting. from rearward rotation, and-the opera-tion 'is quite similar to that above described-'except that the end of brake member 9'iulcr-ums on'pin 7 as will be-Well understood'by those skilled in the art.

Having thus described the invention with particularit-y With reference to the preferred embodiment of the same itwill be obvious to those skilled in the art, after understandnon-rotatable member, an expansible brake Y ing the invention, that many changes and modifications may be made Without departing from the spirit and scope of the invention, and I aim in the appended claims to ,cover such changes and modifications as are Within the scope of the invention.

1' WhatI claimis: A

l. Iny an internal expanding brake, the combination of a rotatable brakel drum. a

shoe comprising 'a plurality of relatively heavy brake elements flexibly connected, re'- s1l1ent means for positioning said shoe in non-braking position about saidnon-rotatable member as a pivot, a limit stop acting to limit thea'ction of' said resilient posi- Y tioning means, means for moving one of said brake elements into braking engagement with said drum to force by its peripheral movement the connected brake elementV into braking contact with said drum, andresilient means for normally holding said first and said second elements out of braking position. y

2. In an internal expanding brake, the combination of a rotatable brake drum. a non-rotatable member, an expansible brake shoe comprising a plurality of relatively rigid brake elements, an anchor stop carried by said non-rotatable member on which said brake shoe is adapted to be pivotally positi'oned in nonbrak'ing position, resilient means for positioning said shoe in non-braking position about said pivot, an adjustable limit stop to limit the action of said resilient positioning means tol thereby center said shoe Within said drum, means' for moving one of said brake elements i't'o braking position to force by its per'pheral movement the connected brake element into braking contact, said anchor stop limitingthe movement of said connected brake elements at the time when force is applied thereto by said first brake element, and resilient means for normally holding said first element out yof braking engagement. n

p 3. In an internal expanding brake` the combination of a rotatable brake drum, a non-rotatable member, anrexpansible brake shoe"comprising aplurality of relatively rigid brake elements, anchor Ystop means carried by said non-rotatable member ony which said brake shoe is adapted to-be pivotally positioned in non-braking position, resilient means for positioning said yshoe in non-braking position about said pivot means,

limit stop meansv to limit the action ot said resilient positioning means -to thereby center said shoe Wltlnn said drum, means for so y.

movingl one of said brake elements into p brakingposition to force by its peripheral movementthe connected brake elements into braking contact, said anchor stop means limiting the' `movement of said lconnected brake elements at the time when force is applied theretoby said first brake element, and resilient v'means 'for normally holding said brake elements' out of braking engagement.

4. In aninternal expanding brake, the combination of a rotatable brake drum, a non-rotatable member, an eXpansible-brake -shoe having two adjacent ends adapted for movement toward and from each other and other, anchor stop means carried by said non-rotatable member and acting as pivot means about which said brake shoe is centered and also actingto limit the circumferential movement of the brake shoe, re,- silient m'eans acting to move said shoe about its pivotal support Ain one direction, an adjustable'stop for limiting said resilient action to thereby center saidshoe within said drum when said shoe is 'ir-,Lits normal nonbraking position, resilient."means for normally holding the tWo adjacent ends of said shoe toward each other and out of braking engagement with said drum, and means for separating the two ends of said shoe, Whereby one element of said shoe Willbe moved into braking position to force by its circumferential movement the connecting brake element into braking contact.

in cooperating abutting engagement 'with Y said bearing portion and having their other ends pivotally and( adjustably connected together, resilient means for normally holding said brake shoes against said bearing portion and away from said drum, additional resilient means for'peripherally centering said brake shoes With respect to said drum about said bearing portion, as a piyot, and

means for moving one of said brake shoes away from said bearing portion and both of said shoes into engagement with said drum against the action of said resilientmeans.

6. In an internal expanding brake, the combination of a rotatable brake drum, a non-rotatable member, a brake element with one free end bearing aga-inst said non-rotata-- ble member, resilient means adapted to yieldably hold said end against said. member, a second brake element with one free cnd bearing against said non-rotatable member, a second resilient means less resilient than the first adapted to yieldably hold the free end of said second brake element against said member, means for pivotally connecting the other ends of said brake elements together, and a third resilient means less resilient than the second adapted' to normally yieldably hold said brake elements in proper position Within said drum about said non-rotatable member as a pivot.

7. In an internal expanding brake, the combination of a rotatable brake drum, a non-rotatable member, a brake element with one free end bearing against saidnon-rotatable member, resilient means adapted toyieldably hold said end against said member, a second brake element With one free end bearing against said non-rotatable membcr, a second resilient means less resilient than the first adapted to yieldably hold the free end of said second brake element against said member, means for pivotally connecting the other-ends of said brake elements together. a third resilient means less resilient than the second adapted to normally yieldably hold said brake elements in proper position Within said drum about said nonrotatable member as a pivot, and means to move one of said brake elements away'from said pivot and both of said brake elements into braking engagement vWith said Idrum.

-8. In a brake mechanism,.a drum, .a selfenergizing brake therefor comprising a plurality of shoes connected by an articulated joint which comprises means for adjusting saidshoesrelative to each other,` additional adjustment means for adjusting said 'shoes relative to said drum, anchoring means for said'brake, said shoes and articulated joint being floatingly supported for limited movement circumferentially of said drum in either direction and relative to said anchoring means, and actuating means separate from said anchoring means for moving said shoes into engagement With said drum.

9. In a brake mechanism, a drum, a selfenergizing brake therefor comprising a plurality of shoes connected by an articulated joint which comprises means for adjusting said shoes relative to each other, additional adjustment means vfor adjusting said shoes relative to said drum, anchoring means for said brake, said shoes and articulated joint being' lloatingly supported for limited movement circumferentially of saidv drum in either direction and relative to said anchoring means, and afloating device engaging both shoes and separate from said anchoring means for moving said shoes into engagement with said drum.

In testimony whereof I have signed my name to this specification. i

GUSTAV. W. CARLSON. 

